1. Field of the Invention
The invention relates to a method for producing a finished part comprising a zone which forms a door for an airbag and is designed to allow a passageway for the airbag to be created, as well as to such a part and to an assembly comprising the part.
More particularly the invention has applications in the field of automotive interior design, where it is especially relevant to the production of facia panels and door panels.
2. Description of the Prior Art
The object of the invention is to find a straightforward, reliable and inexpensive way of producing durable and reliable parts that enable a passageway to be created in a satisfactory manner.
In order to produce such a part, U.S. Pat. No. 5,395,668 and FR-B-2 725 950 disclose a method featuring the following steps: a) producing a part comprising a support element made from plastics material(s) which is of reduced thickness compared to its other dimensions, and a connecting sheet which extends substantially along the surface of said support element, b) incorporating in the part the special zone which forms a door delimited by a periphery constituted by an embrittled portion which has been mechanically weakened between two extremities and by an articulating portion which defines, between said two extremities, an articulation axis overlapped by the sheet.
However, this method is not entirely satisfactory. In particular, as far as the airbag is concerned, opening the door gives rise to fractures and even cracks, which tend to propagate within the part. Since these fractures or cracks are not restricted to the articulating portion, there is a danger of fragments of said part breaking away and being projected at the occupants of the vehicle and injuring them. Furthermore, there is a dispersion of the force deployed by the airbag, requiring the airbag to exert very great pressures to succeed in opening up the door.
Although it would have been possible to employ quality materials that are able to withstand stresses without fracturing, this solution is nevertheless comparatively expensive.